A team of researchers from the architecture and geosciences departments at Texas A&M are using the latest digital-imaging technology to not only preserve Alcatraz Island's history, but also rediscover pre-penitentiary fortifications that were built during the Civil War-era. If the work is successful, the project's principle investigator says the data could be used to create 3-D renderings of tunnels and buildings that haven't been seen since the late 19th Century.
Mark Everett, professor of geology and geophysics, and doctoral student Tim de Smet have been using ground-penetrating radar to peek about 12 to 15 feet beneath the surface of the recreation yard and parade grounds that were built during the penitentiary years, when some of America's most dangerous criminals were kept on the island near San Francisco Bay.
"This is the first time, that I'm aware of, that geophysics has been brought in to try to image the historical Civil War-era part of Alcatraz history," Everett said.
So far, the radar has discovered remnants of underground tunnels and embankments constructed by soldiers in the mid-1800s, when the island was called Fortress Alcatraz.
The island's fortifications, which only served as a federal prison for 29 years, were first constructed as a military outpost. At one time, the fort held 105 canons armed for the Bay area's protection.
De Smet said one of the big finds so far has been the south caponier, a long concrete and brick structure that extended out into the ocean. From the caponier, the soldiers could fire canons at different angles.
The fortress became a military prison during the Civil War, according to research Alcatraz historians provided the team.
The island was a long-term detention facility for military prisoners from 1868 until 1933, when it became a federal prison housing inmates such as Al Capone and George "Machine Gun" Kelly.
The prison was officially closed on March 21, 1963, by then-Attorney General Robert Kennedy.
Working at Alcatraz
Everett, an expert in near-surface geophysics, was invited to the island by A&M architecture professor Robert Warden, who is working on historical preservation of the federal prison. Warden was called in by the National Parks Service to map out the "puppy steps" and several other sites around the prison grounds. His team used a state-of-the-art laser scanner to create 3-D images of the locations.
Everett's work on Alcatraz utilized ground-penetrating radar to capture data that is digitally transformed into visual interpretations of the tunnels. The result is several different perspectives of the scanned areas, from vertical slices to a full 3-D cube.
Everett and De Smet made three trips to San Francisco over the last year and a half. The pair spent about 10 days total on the island, scanning with students and professors from California State University, Chico. Texas A&M graduate Tanya Komas was one of the CSU representatives who was directing students in the preservation efforts. Komas is the director of Concrete Industry Management at CSU, Chico.
"We'd go out on the first ferry in the morning with the staff and come back on the last boat with the tourists," Everett said.
De Smet would move the radar along tightly grouped rows marked off with strings at both sites. The radar captured data at various depths to create multiple profiles and images, de Smet said.
The radar information is brought back to a lab in the Michel T. Halbouty Geosciences Building on the Texas A&M campus, where it is cleaned up by de Smet and digitally transformed into an image. The research is part of de Smet's dissertation research.
"The technical side is long and laborious work," Everett said.
Work that will pay off with a digital 3-D cube that is created through various mathematical techniques, according to de Smet.
The images, he said, are like slices of the ground that have been reassembled in the computer.
"These time-slices really are like looking at slices in time from a bird's eye view above the survey, as the greater depths are actually from earlier periods, showing the transformation of the site from the earliest time period to the surface present," de Smet wrote in an email.
Unfortunately, the picture becomes less clear the farther the radar travels. Data recovered from the most recent trip in December will provide a higher resolution because the depth of the scan was relatively shallow.
More project possibilities
Everett said the project is about six weeks away from completion. The data will be turned over to the National Parks Service officials for review, he said.
The project's future is uncertain beyond that point, Everett said, because the National Parks Service will have to decide how it wants to move forward with the subterranean exploration.
De Smet said the team intends to publish the research in a major journal, but did not specify which one.
Everett said there are no plans to excavate the parade grounds and recreation yard. If they did, Everett said, he would be excited to see if there are Civil War-era canons and weapons still stored in the caves, most of which were covered up with brick walls during the prison's construction.
If given the opportunity, Everett and de Smet said they would like to explore more of the 22-acre island's subsurface.
"I am hopeful we can define some of the already known features in greater detail as well as see some other structures like the magazine, school room and engineer's office from the earliest period of the island's history as a fort, during the Civil War," de Smet said in his email.
The data that has been collected could prove useful beyond the project's completion. Everett said he would be interested in working with Warden in the architecture department to see how 3-D printing could help recreate the inaccessible ruins.
Regardless of future projects, Everett said, the discoveries made so far are important milestones for the National Parks Service.
"It's absolutely important work that they are doing. The Parks Service really does historic things," he said.